Air bag deployment chute

ABSTRACT

An integrated air bag support structure that functions to dissipate excessive energy from a door panel during air bag deployment. The air bag support structure includes a support base for attachment to the rear side of a substrate. The support base is configured to surround a door support panel and both are configured for attachment to the rear side of a substrate in an area that is pre-weakened to define an air bag deployment door in a vehicle instrument panel or a steering wheel air bag module. An air bag chute tube extends downward from the support base and contains a plurality of skirt walls that surround an air bag container to define the path for deployment of the air bag from beneath the substrate. The door support panel is generally co-planar with the support base when attached to the substrate, but is separated from the support base by a gap on all four sides. A compound hinge element extends between one of the skirt walls of the air bag chute tube and one edge of the door support panel, and includes a plurality of pivoting elements and an arm extension. Strengthening bars are located on the open end of the chute to maintain the rectangular shape of the chute during assembly with the air bag container. The strengthen bars also function to both prevent vibration and to reinforce the side walls during air bag deployment and prevent the deployment forces from separating the air bag container from the air bag support structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to the commonly assigned application serialno. (19027), filed contemporaneously herewith and entitled “ENERGYABSORBENT HINGE FOR AN AIR BAG DEPLOYMENT DOOR.”

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of air bag deployment systems for anautomotive vehicle and more particularly to the area of an air bag chutestructure.

2. Description of the Related Art

In this technology field, there have been several attempts to provide apassenger air bag chute integrated with a hinged deployment door and asupport structure for underlying a vehicle interior panel.

U.S. Pat. No. 6,467,801 describes an air bag deployment chute with ahinge member that is attached between the door and a base reinforcementportion that surrounds the door.

U.S. Pat. No. 7,178,825 describes several embodiments of an air bagdeployment chute. Several embodiments show an integral structure thatcontain windows for interconnecting with hooks extending from an air bagcontainer. Other embodiments show add-on reinforcements to the windows.

U.S. Pat. No. 7,275,759 shows a multi-piece air bag chute with sidewindows that are formed to collapse during air bag deployment and allowportions of the chute and outer cover to move outwards from thecontainer during air bag deployment.

BRIEF SUMMARY OF THE INVENTION

The inventive concept is directed to an improved method and apparatus,for use in an air bag deployment system, that includes an air bagdeployment structure and chute formed to have reinforcing members tomaintain a rectangular chute opening during air bag installation and toprevent separation of the chute from the air bag container due totear-through of windows during air bag deployment.

The inventive concept includes an integrated structure with a supportbase for attachment to the rear side of a vehicle interior substrate.The support base is configured to surround a door support panel forattachment to the rear side of the substrate in an area that ispre-weakened to define an air bag deployment door in a vehicleinstrument panel or a steering wheel air bag module. A rectangular airbag chute tube extends downward from the support base and contains aplurality of skirt walls for surrounding an air bag container and todefine the path for deployment of the air bag from the air bagcontainer. The door support panel is generally co-planar with thesupport base when attached to the substrate, but is separated from thesupport base by a gap on all four sides. A hinge element extends betweenone of the skirt walls of the air bag chute tube and one edge of thedoor support panel, and includes a pair of pivoting elements and an armextension. The skirt walls of the chute form a rectangular openingopposite the door support panel for accepting insertion of the air bagcontainer during assembly. Windows are provided in at least one skirtside wall of the chute for receiving hooks that extend from the air bagcontainer. In addition, strengthening bars are formed beneath thewindows and adjacent the chute opening. The strengthening bars functionto maintain the rectangular shape of the chute opening during assemblywith the air bag container and to subsequently prevent contact betweenthe larger chute and the smaller air bag container that would otherwisecause noise during vehicle operation, due to vibrational contact. Thestrengthening bars also prevent the chute from becoming detached fromthe air bag container hooks by providing added mass to the skirt wallbelow the windows.

Therefore, it is an object of the inventive concept to provide animproved energy management method and system for an air bag deploymentsystem that reduces the energy present on the door member during air bagdeployment and the resultant forces which may otherwise cause separationof the air bag chute from the air bag container.

It is another object of the inventive concept to provide an improved airbag chute that is integrated in structure with reinforcement bars belowthe skirt wall windows.

It is a further object of the inventive concept to provide an integratedstructure that embodies the claimed features.

A more complete description of an embodiment of the inventive concept ispresented below.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of a vehicle instrument panel illustratingair bag deployment areas in which the present inventive concept may beemployed.

FIG. 2 is a cross-sectional plan view taken along section line 2-2 inFIG. 1, which shows an embodiment of the inventive concept connected toa substrate and an air bag container assembly.

FIG. 3 is a top plan view of an embodiment of the inventive conceptprior to installation in a vehicle air bag deployment system.

FIG. 4 is a cross-sectional perspective view taken along section line4-4 in FIG. 3

FIG. 5 is a perspective bottom view of the embodiment shown in FIGS. 3and 4.

FIG. 6 is another perspective bottom view of the embodiment shown inFIGS. 3-5.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 represents a typical vehicle instrument panel 10 into which theinventive concept may be installed. Additionally, the inventive conceptis suitable for inclusion in a steering wheel air bag module 20.

In FIGS. 2, 3 and 4, the support base 101 of air bag deploymentstructure 100 is shown to have upper and lower surfaces. The uppersurface of support base 101 contains a plurality of welding ribs 118 tofacilitate attachment to the lower surface 11 of substrate 14 with avibration welding process. (Of course other types of attachment such asultrasonic welding, adhesives and other commonly known techniques may beacceptable substitutes, provided they preserve the energy absorbingcharacteristics described herein.) A door support panel 104, containingwelding ribs 119, is also attached to the lower surface 11 of substrate14, but within an area defined as the air bag deployment door by thepre-weakened seams 12 and 13. In this configuration, the door tear seam12 is pre-weakened to the extent that the outer surface of instrumentpanel 10 and the substrate 14 will completely rupture upon deployment ofthe air bag. Seam 13 is a hinge seam and is formed to provide a pivotpoint for the substrate and outer skin of the instrument panel 10.Therefore it may be pre-weakened to a lesser extent than door seam 12.

The air bag deployment structure 100 is formed as a one piece molding ofa flexible material such as Dexflex™ or other material that exhibitsequivalent or superior ductility at very cold temperatures at least to−30° C. and good toughness at high temperatures at least to 90° C. Othermaterials such as TPO (Thermoplastic Olefin), TPE (ThermoplasticElastomer or TEO (Thermoplastic Elastomer Olefin) could be substituted.It is believed that various pieces could be separately formed and joinedtogether to replicate the one piece molded embodiment. If that is done,care will have to be made in order to obtain the energy management thatis offered by the integration of the various elements that make up thedisclosed structure.

Support base 101 is a generally planar flange that is substantiallycoplanar with the door support panel 104. As shown in the figures, thereis a slight curvature that is intended to correspond to the substratesurface to which the structure attaches. Such a substrate could becurved or perfectly flat. For purposes of this discussion, the supportbase 101 and the door support panel 104 are described as generallyplanar to mean that they are configured to be attached to the undersideof the substrate 12 that is generally smooth and continuous.

In the depicted embodiment, an alignment slot 137 is provided in anextension from support base 101. Although not shown, the substrate 12may have a protrusion formed therein and extending from its lowersurface to provide a keying feature that assists in the correctplacement of the support structure 100 prior to being welded to thesubstrate. Apertured tabs 131, 133 and 135, extending from support base101, are used to accept other protrusions extending from the lowersurface of substrate 12.

A test tab extension 139 is shown as having deformable ribs 138 that areidentical in content to deformable ribs 118 and 119 for attachment tothe corresponding lower surface area of the substrate 12 during the samevibration welding process. The test tab extension 139 allows the weldingvendor, the assembler, or subsequent customer to perform non-destructivequality control testing by applying a pull pressure to the tab andthereby ensure that the entire weld of the support structure 100 to thesubstrate is of the same quality.

Door support panel 104 and support base 101 are separated by a gap 112so that door support panel 104 is not directly attached to the supportbase 101. The support base 101 extends under the pre-weakened door seams12 and 13 and therefore provides resistance to inward pressures that maybe applied to the outer surface of the instrument panel 10. In thedepicted embodiment, several apertures 110 are shown in door supportpanel 104. Apertures 110 are positioned to reduce the mass of the doorsupport panel 104 without affecting its support or attachmentproperties.

An air bag chute tube is formed by skirt walls 105, 106, 107 and 108which extend downward from support base 101. In this embodiment, the airbag chute tube has a rectangular configuration defined by end skirtwalls 105 and 107, and side skirt walls 106 and 108. Angle gussets 127,128 and 129 are spaced along the outside of the skirt side and end wallsto provide added strength and some rigidity between the support base 101and the air bag chute tube.

A hinge element 200 extends between the side skirt wall 108 and hingeedge 107 of door support panel 104. Hinge element 200 includesrespective first and second pivoting elements “A” and “B” and an armextension 103. From the end, it can be seen that the first pivotingelement A is formed with a downwardly directed curve having one endconnected to the inner side of side skirt wall 108 and the other endconnected to said second pivot element B. The second pivot element B isformed with an upwardly directed curve having one end connected to thefirst pivot element A and the other end connected to extension arm 103.Extension arm 103 extends upwards from second pivot element B to a hingeedge 107 of said door support panel 104. Each pivot element is an axialextension substantially parallel to each other and to the edge of thedoor panel to which the arm extension 103 is connected. Each pivotelement, as well as arm extension 103, extends approximately the fulllength of the hinge edge 107.

The longer side skirt walls 108 contain several window apertures 114 and116 for engagement with a corresponding number of attachment hooks 304and 306 extending from an air bag container 300. Window apertures 114and 116 have pressure tabs 115 and 117 that bear against the insertedhooks to tighten the engagement connections and prevent rattling fromoccurring between the air bag container and the air bag chute duringvehicle operation, prior to air bag deployment.

The lower portions of the side skirt walls 108, below the windows 114and 116, contain reinforcement bars 122 and 124. Reinforcement bars 122and 124, in the depicted embodiment, are formed on the edge of the chuteopening and in effect double the thickness of the side skirt wallmaterial at the chute opening. Reinforcement bars 122 and 124 and areformed along the entire length of side skirt walls 108 and function tomaintain the sides of the chute parallel during assembly of the air bagcontainer to the chute. By maintaining the chute side walls parallel,there is less opportunity for noise vibration to be generated betweenthe air bag module and the chute over the life of the undeployed unit.

The bars also prevent hooks 304 and 306 from completely tearing throughthe side skirt walls from their positions in the windows 114 and 116when the air bag is deployed. During air bag deployment, severe pressureis initially present within the air bag container and chute due to theexplosive gases that are generated. Because the air bag container 300 isfixed to the structure of the vehicle at beam 350, the hooks 304 and 306serve to prevent separation of the air bag support structure 100 and theinstrument panel from their intended locations during air bagdeployment. Hooks 304 and 306 interact with side skirt walls 106 and 108below the windows 114 and 116 to contain the pressure and allow thechute to remain intact, while the pressure is directed to the doorsupport panel 104. The directed pressure forces the tear seams 12 torupture and the air bag to deploy. Some prior art applications use metalside walls in air bag chutes to prevent tearing. In the presentinventive concept where a thermoplastic material, such as noted above,is molded to form an integrated structure 100, the double thicknessstrengthening bars 122 and 124 combine with the side walls 108 and 106to prevent the hooks from completely tearing through the skirt walls andallowing separation of the air bag support structure 100.

It can be seen from the drawings and accompanying explanation, that thepresent inventive concept is a unique improvement over conventional airbag deployment support structures and methods of managing deploymentenergy. And while the embodiment shown here is a preferred embodiment,it shall not be considered to be a restriction on the scope of theclaims set forth below.

1. An air bag deployment structure for use in an air bag deploymentsystem of an automotive vehicle, comprising: a support base forattachment to the rear surface of an occupant facing substrate; saidsupport base having upper and lower surfaces and being configured tosurround a defined air bag deployment door in said substrate; and an airbag chute extending downward from said support base and containing aplurality of skirt walls for surrounding an air bag container anddefining the path for deployment of the air bag from beneath saidsubstrate; said skirt walls form a rectangular shaped opening forreceiving said air bag container and wherein a plurality of said skirtwalls are reinforced to maintain said rectangular shaped opening,wherein said support bas, said air bag chute and said reinforced skirtwalls constitute an integrated structure.
 2. An air bag deploymentstructure as in claim 1, wherein at least two opposing skirt walls arereinforced with strengthening bars formed on said walls adjacent to theopening.
 3. An air bag deployment structure as in claim 2, wherein saidstrengthening bars are formed of the same material of said integralstructure and have continuous thickness that adds to the thickness ofsaid skirt wall material at said opening.
 4. An air bag deploymentstructure as in claim 3, wherein said support base, said chute andstrengthening bars are integrally formed as a single structure.
 5. Anair bag deployment structure as in claim 4, wherein said support base,said chute and strengthening bars are integrally formed of athermoplastic material that remains ductile at temperatures down to atleast −30° C.
 6. An air bag deployment structure as in claim 3, whereinsaid air bag chute contains a plurality of windows spaced along at leastone skirt wall to accept and retain hooks extending from said air bagcontainer during assembly.
 7. An air bag deployment structure as inclaim 6, wherein said strengthening bars are located between saidwindows and said chute opening, and wherein said strengthening barsextend continuously below said windows to prevent said hooks frombecoming separated from said skirt walls during air bag deployment. 8.An air bag deployment structure as in claim 6, wherein saidstrengthening bars are located between said windows and said chuteopening, and wherein said strengthening bars extend continuously belowsaid windows to prevent said hooks from completely tearing through saidskirt walls during air bag deployment.
 9. An air bag deploymentstructure as in claim 2, wherein said strengthening bars are attached tothe outer sides of opposing skirt walls at said chute opening.
 10. Anair bag deployment structure as in claim 1, wherein said support baseincludes a test tab extension and both said support base and said testtab extension are welded to said rear surface of said substrate.
 11. Anair bag deployment structure as in claim 10, wherein said extension testtab serves to allow for destructive testing of the weld of said test tabto said substrate without affecting the weld of said support base tosaid substrate.
 12. A method of assembling an air bag deployment systemof an automotive vehicle, comprising the steps of: providing an air bagdeployment structure that includes a support base for attachment to therear surface of an occupant facing substrate; providing said supportbase with upper and lower surfaces configured to surround a defined airbag deployment door in said substrate; providing an air bag chuteextending downward from said support base and containing a plurality ofskirt walls for surrounding an air bag container and defining the pathfor deployment of the air bag from beneath said substrate; andreinforcing at least one of said skirt walls to form and maintain arectangular shaped opening for receiving said air bag container.
 13. Amethod as in claim 12, further including the steps of providing a testtab extension on said support base for attachment to the rear surface ofan substrate simultaneously with said support base.
 14. A method as inclaim 13, further including the step of attaching said support base andsaid test tab extension to said substrate with a vibration weldingprocess.
 15. A method as in claim 12, wherein said step of reinforcingsaid skirt walls includes the step of integrally forming a pair ofstrengthening bars external to said skirt walls.
 16. A method as inclaim 15, wherein said step of integrally forming a pair ofstrengthening bars includes the step of molding said support base, saidchute and strengthening bars of Dexflex™ material.
 17. A method as inclaim 12, wherein said step of providing said air bag chute includesproviding said chute with a plurality of windows spaced along at leastone skirt wall to accept and retain hooks extending from said air bagcontainer during assembly.
 18. A method as in claim 17, wherein saidstep of reinforcing said at least one of said skirt walls includes thestep of providing a strengthening bar between said windows and saidchute opening to extend continuously below said windows to prevent saidhooks from becoming separated from said skirt wall during air bagdeployment.
 19. A method as in claim 18, wherein said step ofreinforcing said at least one of said skirt walls includes the step ofreinforcing opposing skirt walls.
 20. A method as in claim 17, whereinsaid step of reinforcing said at least one of said skirt walls includesthe step of providing a strengthening bar between said windows and saidchute opening to extend continuously below said windows to prevent saidhooks from completely tearing through said skirt walls during air bagdeployment.